Enhanced electrocatalytic properties of plasma-treated MoS2-NiO-PVA nanofibers for hydrogen evolution reaction: A study of surface modifications and charge transfer kinetics

Abstract

In this study, we report the synthesis and characterization of MoS₂-PVA and MoS₂-NiO-PVA composite nanofibers, focusing on their structural, chemical, and electrocatalytic properties before and after plasma treatment. X-ray diffraction (XRD) results verify that the incorporation of NiO nanoparticles into MoS₂-PVA further enhances the crystallinity of the composite, as evidenced by the XRD patterns. Fourier-transform infrared (FTIR) spectroscopy reveals characteristic vibrations of hydroxyl, carbonyl, Mo-S, Mo-O, and Ni-O bonds, providing strong evidence of chemical interactions between MoS₂, PVA, and NiO. X-ray photoelectron spectroscopy (XPS) analysis indicates the successful formation of MoS₂-NiO-PVA nanofibers, with significant interactions between MoS₂ and NiO, enhancing electron transport properties. Scanning electron microscopy (FE-SEM) analysis shows that plasma treatment leads to significant morphological changes, including surface roughening and reduced fiber thickness. Water contact angle measurements demonstrate that plasma treatment improves the hydrophilicity of the nanofibers, facilitating better electrolyte interaction and increasing their electrocatalytic performance. The HER efficiency of MoS₂-PVA and MoS₂-NiO-PVA nanofibers was enhanced through plasma treatment, resulting in a lower overpotential (213 mV) and Tafel slope (135 mV/dec) for MoS₂-NiO-PVA. The increase in capacitance (2.92 mF/cm²) and reduction in charge transfer resistance (R_ct) confirmed improved electrocatalytic activity. The electrocatalyst demonstrated excellent stability, maintaining 92 % of its initial performance after 12 h of continuous operation, as evidenced by cyclic voltammetry at 50  mV/s and a stable potential at 1.5  mA/cm².These enhancements highlight plasma treatment as an effective strategy for optimizing HER kinetics in electrocatalysts. These improvements result from enhanced surface area, hydrophilicity, and accessibility of active sites, making plasma-treated nanofibers promising for energy applications.